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Case 2:
Similarly, when S2 is turned off at t = T1 , the load current flows through the diode D1 and
capacitor C1until the current falls to zero, as shown in Figure below.
Figure: 5.5 Single phase Half Bridge DC-AC inverter with L load
When the diodes D1 and D2 conduct, energy is feedback to the dc source and these diodes are known as
feedback diodes. These diodes are also known as freewheeling diodes. The current for purely inductive
load is given by,
Similarly, for the R
–
L load. The instantaneous
load current is obtained as,
Where,
Operation of single phase full bridge inverter
A single phase bridge DC-AC inverter is shown in Figure below. The analysis of the
single phase DC-AC
inverters
is
done
taking
into
account
following
assumptions
and
conventions.
1)
The
current
entering
node
a
in
Figure
8
is
considered
to
be
positive.
2) The switches S1, S2, S3 and S4 are unidirectional, i.e. they conduct current in one direction.
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Figure: 5.6 Single phase Full Bridge DC-AC inverter with R load
When the switches S1 and S2 are turned on simultaneously for a duration 0 ≤ t ≤ T1 ,
the the input
voltage Vin appears across the load and the current flows from point a to b.
Q1
–
Q2 ON, Q3
–
Q4 OFF ==> ν o = Vs
Figure: 5.7 Single phase Full Bridge DC-AC inverter with R load
If the switches S3 and S4 turned on duration T1 ≤ t ≤ T2, the voltage across the
load the load is reversed
and the current through the load flows from point b to a.
Q1
–
Q2 OFF, Q3
–
Q4 ON ==> ν o =
-Vs
